1. Field of the Invention
The present invention relates to a disk device, and particularly to a disk device for performing a reproducing process or a recording process by rotating a clamped disk.
2. Description of the Related Art
A compact disk whose data are reproduced by a laser type pickup (or an optical pickup) is increasingly used as a storing medium that stores information for software, a database, and the like. Accompanying the increasing use of the compact disk, a disk device (a CD-ROM drive device, or a magnetic optical disk device) that can be incorporated in a chassis of a miniaturized laptop computer has been developed.
The disk device includes a storing medium attaching unit for moving a disk between an attached position where a reproducing process is performed and a detachment position where the disk is attached to the disk device or is detached from the disk device. The disk device further includes a disk rotating mechanism for rotating the disk at a predetermined rotational speed. As shown in FIG. 1A, this disk rotating mechanism includes a turning table 2, a clamping mechanism 3, and a spindle motor (not shown). A disk 1 is clamped (or fixed) to the clamping mechanism (or the fixing mechanism) 3 so as to be fixed to the turning table 2. With the disk 1 being fixed to the turning table 2, the disk 1 is rotated at a high speed.
However, since the clamping mechanism 3 clamps the center part of the disk 1, the disk 1 is warped in the direction indicated by the arrows M in FIG. 1B. As a result, when an optical pickup 5 that is guided by a guide shaft 6 to move in the radial directions of the optical disk 1 performs a reproducing process or a recording process, light emitted from the optical pickup 5 does not strike the thus-warped optical disk 1 orthogonally. For this reason, accuracy in a spot on the disk 1 being struck by light from the optical pickup 5 is reduced, and therefore, recording quality and reproducing quality are greatly reduced.
In order to solve this problem, methods shown in FIGS. 2 to 4 have been proposed. In the method of FIG. 2, the light from the optical pickup 5 is made to strike the optical disk 1 vertically relative to the optical disk 1 by inclining a rotational shaft (not shown) of the turning table 2 by the angle θ1 from the vertical direction.
In the method of FIG. 3, the light from the optical pickup 5 strikes the optical disk 1 vertically relative to the optical disk 1 by inclining the guide shaft 6 by the angle θ2 from the horizontal direction.
In the method of FIG. 4, an object lens 7 of the optical pickup 5 is inclined so as to conform to the warping of the optical disk 1 while the rotational shaft of the turning table 2 is directed vertically, and the guide shaft 6 is directed horizontally. Thereby, the light from the optical pickup 5 strikes the optical disk 1 orthogonally.
However, in the method shown in FIG. 2, since the turning table 2 is inclined, the right side of the optical disk 1 in FIG. 2 opposite the left side of the optical disk facing the optical pickup 5 becomes close to a top cover 8 of the optical disk device. Accordingly, in the worst case, the optical disk 1 makes contact with the top cover 8 at the position indicated by the arrow P of FIG. 2, and the optical disk 1 can be damaged. This becomes a big problem in the case of an optical disk device that is incorporated in equipment such as a laptop computer, which is desirably thin.
Furthermore, in the method shown in FIG. 3, in order to incline the guide shaft 6, various components such as a screw shaft and a stepping motor for driving the optical pickup 5 must also be inclined in accordance with the inclination of the guide shaft 6. As a result, assembling quality or accuracy is degraded. In addition, since the stepping motor is arranged so as to be inclined, the thickness of the optical disk device (or vertical size of the optical disk device) becomes larger than that in a case where the stepping motor is horizontally arranged.
Further, in the method shown in FIG. 4, when the object lens 7 has coma aberration, accuracy in a spot on the disk being struck by the light from the optical pickup 5 is reduced, and recording/reproducing characteristics can be degraded.